Billet and method of extrusion thereof



July 16, 1968 F. J. FUCHS, JR

BILLET AND METHOD OF EXTRUSION THEREOF Filed April 8, 1966 2 Sheets-Sheet 1 FIG. 2

@ 111. W i 11W m/vavrw? F. J. FUCHS, JR.

IQpI LQQ ATTORNEY July 16, 1968 F. J. FUCHS, JR 3,392,562

BILLET AND METHOD OF EXTRUSION THEREOF Filed April 8, 1966 2 Sheets-Sheet '2 United States Patent 3,392,562 BILLET AND METHOD OF EXTRUSION THEREOF Francis J. Fuchs, Jr., Princeton Junction, N..I., assignor to Western Electric Company, Incorporated, New York, N.Y., a corporation of New York Filed Apr. 8, 1966, Ser. No. 541,220 Claims. (CI. 72-60) This invention relates to a billet and a method of extrusion thereof, and more particularly to a billet having means at a trailing end thereof for decelerating the speed of the billet during a final portion of the extrusion of the billet through a die.

In the art of extruding billets, the problem has often occurred that the speed of the billet is accelerated during a final portion of the extrusion process due to a decrease in friction between the billet and the walls of the chamber on each side of the extrusion orifice as the trailing end of the billet approaches the orifice. The billet tends to shoot out from the orifice during this final portion of extrusion creating a safety hazard, causing imperfections at one end of the extruded product and resulting in a wastage of material. Prior attempts to overcome this problem have used two or more orifice dies in series for decelerating the billet.

Moreover, certain materials which are brittle at atmospheric pressures may be rendered ductile and, thus, capable of being extruded by subjecting them to high fluid pressures. It is, therefore, desirable to provide for fluid pressurization of billets made of such materials during an extrusion operation upon them.

It is an object of this invention to provide a new and improved billet and method for extrusion thereof.

Another object of the invention is the provision of a billet which is adapted to coact with a single die through which it is extruded so that the speed of the billet is decelerated during a final portion of the extrusion operation.

A further object of the invention is to provide a method for applying high pressure to a billet to render it more ductile, while causing a deceleration of the billet during a final portion of a simultaneous extrusion operation upon the billet.

Still another object of the invention is to provide a billet flared to the diameter of an inner one of a pair of concentric rams to be forced through an extrusion die by the inner ram in a fluid-filled chamber, the outer ram simultaneously moving to pressurize the fluid in the chamber so as to render the material of the billet more ductile, while the flared end of the billet passes last through the die to decelerate the speed of the billet during a final portion of the extrusion operation.

With these and other objects in view, the present invention contemplates a billet having a structure formed at one end which will cooperate with a die through which it is to be extruded to cause the speed of the billet to be decelerated during a final portion of the extrusion operation. More particularly, the billet may be flared at one end and extruded from a fluid-filled chamber by being forced through the die by fluid pressure, a ram acting to pressurize the fluid to both cause the extrusion force and simultaneously render the billet more ductile for extrusion. Alternatively, two concentric rams may be used, an outer ram causing fluid pressurization while an inner ram directly contacts the billet to provide the extrusion force. In practice of the method, the billet is initially placed in the extrusion die so that the flared end passes through the die during the final portion of the extrusion operation and functions to decelerate the extended end of the billet.

Other objects and advantages of the present invention will be apparent from the following detailed description when considered in conjunction with the accompanying drawings, wherein:

FIG. 1 is a side view partly in section, showing a billet according to the invention which is positioned in a suitable high pressure extrusion chamber, between a ram at one end thereof and a die at the other end;

FIG. 2 is a side view similar to FIG. 1, showing the apparatus with the billet partially extruded through the die;

FIG. 3 is a side view similar to the preceding figure, showing the apparatus during a final portion of the extrusion operation; and

FIG. 4 is a side view similar to FIG. 2, showing an alternative ram structure employing a pair of concentric rams.

As is known, many materials exhibit an increase in ductility upon being subjected to fluid pressure. If the hydrostatic pressure imposed upon such material is sufficiently high, plastic flow of the material will result, rendering extrudable materials which at lesser pressures are too brittle to successfully undergo extrusion. One example of a material having this property is molybdenum. Further information may be obtained by reference to Dr. Percy M. 'Bridgmans text, Large Plastic Flow and Fracture, published in 1952 by McGraw-Hill Book Company.

Referring now to FIG. 1, a billet 11 is provided for extrusion through a die 12. The billet 11 is an elongated member which may be composed either of a material, such as copper, which is ductile at atmospheric pressure, or of a material, such as molybdenum, which is extrudable only when subjected to high pressure. The billet may be formed by any welLknown process such as forging, casting or machining. A trailing end 13 of the billet 11 is shaped in such manner that it will coact with the die 12 to cause the billet to be decelerated during a final portion of the extrusion operation. This effect is desired to counter the tendency, otherwise present, for the billet to be accelerated during the final phase of extrusion. The trailing end 13 has a portion 14 thereof flared outwardly from a body portion 16 of billet 11. The flared portion 14 may be in the form of a frusto-conical surface 17, continuously increasing in diameter from the body portion 16 to the trailing end 13. The body portion 16 and forward end 18 of the billet 11 may be of constant diameter which may be considerably greater than the diameter of the extrusion orifice.

An apparatus for extrusion in accordance with the practice of the method may include a high pressure chamber 19 filled with an incompressible fluid 21 such as silicon oil or the like, and having at one end the die 12. Valved facilities (not shown) may be provided for entry of fluid into, and discharge of fluid from, chamber 19. Die 12 has extending through it an extrusion orifice 22. A beveled portion 23 of the die surrounds the orifice 22 on the surface 24 of the die facing into chamber 19. A ram 25, extending from a high pressure fluid cylinder 26, may be provided for movement into the chamber 19 to form the end of the chamber opposite to die 12. Cylindrical or otherwise shaped walls 27 of a die block 28 form the side walls of chamber 19 to completely enclose the chamber. A seal 29 may be located between the die 12 and chamber side walls 27 to prevent fluid leakage around the die. A bolster plate 30 may be used to support the die. An opening 31, preferably larger than extrusion orifice 22, is locate-d in bolster plate 30 in alignment with orifice 22.

In practicing the method of the invention, the billet 11 may be shaped by any well-known process as, for example, by forging, casting or machining. The billet is placed in chamber 19 with forward end 18 contacting the beveled portion 23 of the die 12 and in alignment with extrusion orifice 22 (see FIG. 1). Chamber 19 is filled with fluid 21. Ram 25 is then moved by the application of a pressurized fluid to cylinder 26 whereupon the ram 25 applies a force to the fluid 21 in chamber 19 to pressurize the fluid 21. Pressurized fluid 21 acts upon the trailing end 13 of billet 11 and there results a net force on the billet in the direction of die 12. The billet is now forced through extrusion orifice 22 by the increased pressure, as is shown in FIG. 2. The high pressure of fluid 21 also acts to render the billet more ductile and, thus, more easily extrudable. The trailing end 13 having thereon flared portion 14 passes last through orifice 22. As is apparent in FIG. 3, the flared portion 14 of billet 11 and the beveled portion 23 of die 12 interact to cause the billet to be decelerated during a final portion of the extrusion operation. This counters the tendency, otherwise present, for billet 11 to be accelerated due to a decrease in friction between the billet and surface 24 of die 12 as the extrusion is completed. The degree and length of taper of frusto-conical surface 17 of the flared portion 14 may be varied to control the deceleration of billet 11. If the angle between the body portion 16 and the surface 17 is decreased, there will be a greater deceleration effect. In addition, the increase in diameter of the tapered portion of the billet is accomplished by an increase in the decelerating effect.

An alternative practice of the method of the invention is illustrated in FIG. 4 of the drawings, in which the ram structure of the embodiment of FIGS. l3 is modified. Like parts are numbered in accordance with the reference numerals of FIGS. 13.

In place of a single ram 25, two concentric rams are used. An inner ram 32 is surrounded by a tubular outer ram 33. Inner ram 32 has a diameter substantially equal the diameter of flared trailing end 13 of billet 11. Outer ram 33 fills substantially all of the space between inner ram 32 and chamber walls 27. A pair of concentric cylinders (not shown) may be used to operate rams 32 and 33 in the manner of cylinder 26 of the embodiment of FIGS. 1-3. The outer structure of the embodiment of FIG. 4 is similar to that of FIGS. 1-3.

In practice of the method with this apparatus, billet 11 is first placed in chamber 19 coaxially with extrusion orifice 22 and with the forward end 18 contacting the beveled portion 23 of die 12. Chamber 19 is filled with fluid 21 to submerge the billet. Inner ram 32 is then brought into coaxial contact with the flared trailing end 13. Inner ram 32 is moved in the direction of billet 11, causing extrusion of the billet through the die with flared end 13 passing last therethrough to decelerate the billet during a final portion of the extrusion. At the same time as inner ram 32 is moved in the direction of die 12, outer ram 33 is also displaced to pressurize the fluid 21 in chamber 19. Billet 11 is, thus, subjected to high pressure during the extrusion operation, rendering its constituent material more ductile. A normally ductile material, such as copper, may be made more ductile by this pressurization, facilitating the extrusion. Moreover, billets of a material such as molybdenum, capable of being rendered sufficiently ductile for extrusion by subjection to high fluid pressures, may be extruded by the method of this invention.

It is to be understood that the billet and method of extrusion described above are intended to be simply illustrative of the article and of apparatus for carrying out the method of this invention. Many other modifications may be made without departing from the invention.

What is claimed is:

1. A billet for extrusion through a die having an orifice comprising an elongated member composed of an extrudable material and having means on the billet at its trailing end for decelerating the speed of the member in passing through the die.

2. A billet as defined in claim 1, wherein said means for decelerating the speed of the elongated member comprises a flared portion at the trailing end of the member.

3. A billet as defined in claim 1 for extrusion through a die having a beveled portion extending to said orifice, wherein said means for decelerating the speed of the elongated member comprises a portion of said elongated member at its trailing end angularly flared to an enlarged diameter to coact with said beveled portion to decelerate the speed of said member as its trailing end passes through said die.

4. A billet as defined in claim 3 wherein the angle of flare and the diameter of the flared portion are selected with respect to the angle of bevel and the diameter of the bevel portion of the die to control the degree of deceleration of the trailing end through the orifice.

5. A billet for extrusion in a fluid-filled chamber with a die at one end and a pair of concentric rams moving from the other end, said billet comprising:

an elongated extrudable member with an end flared to a diameter substantially equal to the diameter of the inner one of the concentric rams for engagement with said inner ram whereupon said member is extruded through the die by said moving inner ram, said flared end of the member passing last through the die and acting to decelerate the member during a final portion of the extrusion, while the outer moving ram acts to increase the fluid pressure in the chamber.

6. A method of extruding an elongated billet with a flared end through a die comprising:

extruding said billet with the flared end thereof passing last through the die to decelerate the billet during a final portion of the extrusion.

7. A method of extruding a billet through a die comprising:

forming a billet of extrudable material with a flared end; and

extruding said billet through said die with the flared end of the billet passing last through the die to decelerate the billet during a final portion of the extrusion.

8. A method, as defined in claim 7, of extruding a billet through a die having a conical beveled surface terminating in an extrusion orifice, wherein the forming step comprises:

forming the flared end with a taper angle and a diameter that reacts the tapered end with the beveled surface to control the degree of deceleration of the billet.

9. A method of extruding a billet through an opening in a die mounted in a chamber wherein said billet is constructed of a material that is rendered more ductile upon being subjected to a predetermined pressure, which comprises:

forming a billet of said material with a forward end of a predetermined diameter greater than said die opening and a flared frusto-conical trailing end; placing the forward end over said die opening;

filling said chamber with fluid to submerge said billet;

and

pressurizin-g said fluid to subject said billet to said predetermined pressure whereupon said billet is rendered ductile and extruded through said die opening with the frusto-conical trailing end reacting with said die to decelerate the extrusion of the billet.

10. A method of extruding an elongated billet, composed of a material susceptible of being rendered more ductile when subjected to a predetermined high pressure and having at one end a flared portion of a given diameter, in a chamber with an extrusion die at one end and a pair of independently driven, concentric rams at the opposite end, the inner ram being of a diameter substantially equal to that of the flared portion of the billet, comprising:

placing said billet against the die with the flared end of the billet farthest from the die;

filling said chamber with fluid to submerge said billet;

bringing said inner ram into contact with the fllared end of the billet;

displacing said inner ram in the direction of the billet to extrude the billet through the die with the flared end of the billet passing last through the die to decelerate the billet during a final portion of the extrusion; and, simultaneously pressurizing the fluid in the chamber by displacing the outer ram, in the direction of the die to subject the billet to said predetermined high pressure to render it more ductile.

References Cited UNITED STATES PATENTS Hoopes.

Bridgman.

Jaskowiak.

Gerard.

Schnettker 72--271 

1. A BILLET FOR EXTROSION THROUGH A DIE HAVING A ORIFICE COMPRISING AN ELONGATED MEMBER COMPOSED OF AN EXTRUDABLE MATERIAL AND HAVING MEANS ON THE BILLET AT ITS TRAILING END FOR DECELERATING THE SPEED OF THE MEMBER IN PASSING THROUGH THE DIE. 